Adolescent and young adult (AYA) hematopoietic stem cell transplantation (HSCT) patients face a variety of well-documented physical and emotional challenges. In addition to undergoing a life-threatening procedure that involves an intense treatment regimen and lengthy hospital stay, these patients face a protracted 12-month recovery period marked by numerous physical, emotional and psychosocial challenges, such as coping with immunosupression and its socially isolating effects; fatigue, adherence to complex medication regimens; and meeting hydration and nutrition requirements. Failure to meet these challenges not only engenders distress, anxiety and depression, but can also result in serious consequences to health such as organ damage and/or chronic, severe graft-versus-host disease (GVHD). Unfortunately, it is not uncommon that HSCT patients often fail to meet these challenges or behavioral requirements. This is especially true for AYAs, whose developing autonomy and enjoyment of peers is often juxtaposed with the constraints of cancer treatment. Interventions that assist recipients in successfully completing the requirements of HSCT recovery are needed to maximize physical and psychological health outcomes. The proposed Phase II study will extend and evaluate an online, social, gamified intervention to promote self- management behaviors among AYA allogeneic HSCT recipients during their extended outpatient recovery period. The program, called Stempowerment, utilizes an innovative approach that directly links behavioral objectives to game mechanics within the intervention. The intervention addresses key determinants of self- management behavior, including knowledge, attitudes, adaptive thinking/problem solving, self-efficacy, perceived norms, social support, self-concept/self-esteem, and skill. The overall goal is to maximize positive psychological and physical health outcomes. This project encompasses development of second-generation intervention software that incorporates objective monitoring and mobile technology to assess the targeted behavioral outcomes on a continuous basis, and evaluation of the psychosocial and behavioral impact of the program. Seventy-two AYA allogeneic HSCT patients, 18-29 years old, will be recruited from MD Anderson Cancer Center. We will form an advisory council of HSCT survivors to guide the development of the second-generation intervention. Upon completion of software development, we will evaluate the psychosocial and behavioral impact of the intervention among 64 HSCT patients who will use the intervention for 60 days. Patients will complete patient-reported outcome measures at baseline, at 30 days after starting the intervention, and upon completing the intervention. A one- month post-intervention assessment also will be completed. The goal of this evaluation will be to determine the impact of the intervention during the post-HSCT phase, and to evaluate changes and trends in the psychosocial and behavioral outcomes during the immediate post-HSCT recovery phase. The proposed study will advance scientific knowledge on the impact of game mechanics and social networking on patient behavior, and will provide insights, evidence, and guidance on how to build practical online social intervention systems to support behavioral change in AYAs.